Yeah I thought mine was missing too, its not, page 31 (inside rear cover) explains both 2nd & 3rd, they're the same setup. They're on an angle and there's two of them, one silver and one black, adjust both to the same approx tension.
Still no 3rd for me, pulled apart the tranny yesterday to inspect as it feels like something is binding inside - I cannot roll the car easily, gets caught/jolts then will roll semi freely. Is this normal? This is my first MT (with centre diff, 3 speed and reverse), was previously running mainly tourers (bit boring now I have my GST )